Neagu, N., M. Popa, and V. Orlov. “Stability of Unperturbed Motion Governed by the Ternary Differential System of Lyapunov-Darboux Type With Nonlinearities of Degree Four”. Acta Et Commentationes Exact and Natural Sciences, Vol. 14, no. 2, Sept. 2023, pp. 57-67, doi:10.36120/2587-3644.v14i2.57-67.